• 제어로봇시스템학회논문지
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• 제2권3호
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• pp.148-157
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• 1996

Availability of input trajectories corresponding to desired output trajectories is often important in designing control systems for batch and other transient processes. In this paper, we propose a predictive control-type model-based iterative learning algorithm which is applicable to finding the nominal input trajectories of a linear time-invariant batch process. Unlike the other existing learning control algorithms, the proposed algorithm can be applied to nonsquare systems and has an ability to adjust noise sensitivity as well as convergence rate. A simple model identification technique with which performance of the proposed learning algorithm can be significantly enhanced is also proposed. Performance of the proposed learning algorithm is demonstrated through numerical simulations.

• Korean Chemical Engineering Research
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• 제53권3호
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• pp.350-356
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• 2015

The effects of the zinc oxide (ZnO) preparing process on the performance of inverted organic photovoltaic cells (OPVs) were explored. The morphology and size of ZnO nanoparticles were controlled, leading to more efficient charge collection from device and higher electron mobility compared with nanospheres. Nanosized ZnO particles were synthesized by using zinc acetate dihydrate and potassium hydroxide in methanol. Also, water was added into the reaction medium to control the morphology of ZnO nanocrystals from spherical particles to rods, and $NH_4OH$ was used to prevent the gelation of dispersion. Solution-processed ZnO thin films were deposited onto the ITO/glass substrate by using spin coating process and then ZnO films were used as an electron transport layer in inverted organic photovoltaic cells. The analyses were carried out by using TEM, FE-SEM, AFM, DLS, UV-Vis spectroscopy, current density-voltage characteristics and solar simulator.

• 한국연초학회지
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• 제15권1호
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• pp.98-105
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• 1993

The chemical components of tobacco stalk, stems of tobacco caltivations, were analyzed and reconstituted tobacco sheet were made from the stalk and tobacco hyproducts by rolled and paper reconstitute tobacco sheet making process. The results were summarized as follow 1. In the viewpoint of chemical components, nicotine, total nitrogen and ash content of stalk were lower than those of stems, but crude fiber was two times higher than stems. 2. Reconstituted tobacco sheet of tobacco stalk blended were improved fragility and specific gravity than those of control. 3. Smoke components delivery of cigarette made from reconstituted tobacco sheet of tobacco stalk blended were similar to control cigarette. 4. According to the result of ranking preference test for control and sample cigarette, were not recognized significant at 5 percent level. 5. According to the result of areas test for control and sample cigarette, were not recognized significant at 5 percent level. 6. Optimum stalk blend ratio of reconstituted tobacco sheet manufacturing was from about 20 to 40% to the rolled sheet, and was from about 5 to 10% to the paper making process tobacco sheet.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1718-1723
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• 1991

The determination of a production sequence is an important problem in a batch process operation. In this paper a new algorithm for a near optimal production sequence of N product in an M unit serial multiproduct batch process is proposed. The basic principle is the same as that of Johnson's algorithm for two-unit UIS system. Test results on a number of selected examples exhibit the superiority over previously reported results. In addition, a tabulation technique is presented to calculate the makespan of a given sequence of production for all processing units under UIS mode.

• Korean Chemical Engineering Research
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• 제49권3호
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• pp.306-313
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• 2011

젖산(lactic acid)은 식품, 의약품, 화학약품 등의 원료로서 많이 사용되고 있으며, 생분해성 고분자(biodegradable polymer)인 폴리젖산(polylactic acid)의 원료로서 최근 사용량이 증가하고 있다. 하지만 고비점 물질의 존재와 젖산의 비휘발성은 젖산 분리 및 정제를 어렵게 만든다. 이를 극복하기 위해 분리벽형 반응 증류를 이용하여 비휘발성 물질인 젖산을 에스테르화 반응에 의하여 휘발성이 있는 물질로 전환시킨 후 분리하고 가수분해반응을 이용하여 다시 젖산으로 전환하여, 회수하는 공정을 제안하였다. 제안된 연속적인 젖산회수 분리벽형 반응증류공정의 동특성을 조사하여, 이를 바탕으로 제어계들을 구성하였고 각 제어계들의 성능을 비교하였다.

• 한국안전학회지
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• 제27권3호
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• pp.77-82
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• 2012

The leakage of toxic chemicals impact seriously on human being and environment, therefore during their treatment process, a proper management system is necessary to control their toxic effect. This study was designed to suggest the management regulation that supports business managers and facilities management. There are no extra regulation to control emergency accidents and terrors in chemical facilities. Developed countries like USA operate the management standards to control the toxic chemical and facilities according to their toxicity and processes. In order to solve this problem, we have analysed the advanced nations standard methods of security in chemical plants to study the new security management regulation which helps to prevent the chemical accidents. Especially, in USA, CCPS (Center for Chemical Process Safety), SVA (Security Vulnerability Assessment) and RBPSs (Risk-Based Performance Standards) of DHS (Department of Homeland Security) were invest I gated. On the basis of the results, we have suggested the application methods of the security and safety regulation in Korea.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.48-53
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• 1993

In this paper, it is shown that chaotic nonlinear chemical process can be controlled based on the Poincare map based control algorithm. An isothermal autocatalytic CSTR, which has chaotic dynamics, is successfully controlled and period 2 orbit is generated in a normal chaotic region with small perturbation of the control parameter.

• 제어로봇시스템학회논문지
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• 제10권5호
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• pp.450-457
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• 2004

In this research, the automatic synthesis of knowledge models is proposed. which are the basis of the methods using qualitative models adapted widely in fault diagnosis and hazard evaluation of chemical processes. To provide an easy and fast way to construct accurate causal model of the target process, the Role-Behavior modeling method is developed to represent the knowledge of modularized process units. In this modeling method, Fault-Behavior model and Structure-Role model present the relationship of the internal behaviors and faults in the process units and the relationship between process units respectively. Through the multiple modeling techniques, the knowledge is separated into what is independent of process and dependent on process to provide the extensibility and portability in model building, and possibility in the automatic synthesis. By taking advantage of the Role-Behavior Model, an algorithm is proposed to synthesize the plant-wide causal model, Fault-Causality Graph (FCG) from specific Fault-Behavior models of the each unit process, which are derived from generic Fault-Behavior models and Structure-Role model. To validate the proposed modeling method and algorithm, a system for building FCG model is developed on G2, an expert system development tool. Case study such as CSTR with recycle using the developed system showed that the proposed method and algorithm were remarkably effective in synthesizing the causal knowledge models for diagnosis of chemical processes.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.303-306
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• 1996

We propose a robust tuning method of the quadratic criterion based iterative learning control(Q-ILC) algorithm for discrete-time linear batch system. First, we establish the frequency domain representation for batch systems. Next, a robust convergence condition is derived in the frequency domain. Based on this condition, we propose to optimize the weighting matrices such that the upper bound of the robustness measure is minimized. Through numerical simulation, it is shown that the designed learning filter restores robustness under significant model uncertainty.

• Tribology and Lubricants
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• 제34권3호
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• pp.115-122
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• 2018

Chemical mechanical polishing (CMP) is a hybrid processing method in which the surface of a wafer is planarized by chemical and mechanical material removal. Since mechanical material removal in CMP is caused by the rolling or sliding of abrasive particles, interfacial friction during processing greatly influences the CMP results. In this paper, the trend of tribology research on CMP process is discussed. First, various friction force monitoring methods are introduced, and three elements in the CMP tribo-system are defined based on the material removal mechanism of the CMP process. Tribological studies on the CMP process include studies of interfacial friction due to changes in consumables such as slurry and polishing pad, modeling of material removal rate using contact mechanics, and stick-slip friction and scratches. The real area of contact (RCA) between the polishing pad and wafer also has a significant influence on the polishing result in the CMP process, and many researchers have studied RCA control and prediction. Despite the fact that the CMP process is a hybrid process using chemical reactions and mechanical material removal, tribological studies to date have yet to clarify the effects of chemical reactions on interfacial friction. In addition, it is necessary to clarify the relationship between the interface friction phenomenon and physical surface defects in CMP, and the cause of their occurrence.